In a variety of electronic communication applications, optical modulators may be utilized in high-speed data communications and/or sensory data communications. For example, optical modulators are commonly utilized in analog RF signal transmission applications, digital signal transmission applications, and/or sensory data transfer applications that further utilize optical fibers for data communication. A simple Mach-Zehnder interferometer optical modulator has two optical coupler sections and two arms in which the optical phase of the signal is modulated in the arms of modulator. This conventional design is vulnerable to interference in the second coupler, thus resulting in an intensity modulation. A typical optical modulator may include several optical waveguides, radio frequency (RF) transmission lines, modulation electrodes, DC electrodes, and an optical circuit, which modulate and combine optical signals to achieve a variety of different modulation schemes. Various types of conventional-design optical modulators are typically utilized for a variety of applications. These conventional devices can modulate optical phases, intensity, or both, which are typically generated by a laser.
Conventional lithium niobate optical modulator waveguides are manufactured via an application of a diffusion method. The diffusion method is conventionally able to create a low index contrast optical waveguide. Conventional optical modulator waveguides have low electro-optical efficiency and have large foot prints due to their low index contrast waveguides. The inventor of record in this application, Payam Rabiei, has previously disclosed new methods for creating high index contrast waveguides in U.S. Pat. No. 8,900,899 and US Patent Application Publication 2015/0001175. With these new methods of waveguide manufacturing techniques, a high index contrast optical waveguide can be created in lithium niobate thin films by transferring a thin layer of lithium niobate to a silicon substrate and by creating a ridge waveguide on the lithium niobate thin films. With these new methods of fabrication, high-index contrast optical waveguides and optical modulators can be created much more compactly than conventional diffusion based optical waveguides.
Previously, the inventor of record has also disclosed an optical modulator structure that is based on the high index optical waveguide fabrication method has (P. Rabiei, Optics Express, Vol 21, pp. 25573-25581, 2013). The electrodes were placed in close proximity of the optical waveguide on top of the electro-optical material and no etching was performed to form a mesa structure.
As the electro-optical modulator circuit complexity increases, some novel fabrication steps and production techniques may be desirable to enable formation of advanced modulators in electro-optic materials. Various optical circuits that are used to achieve optical signal modulation are typically large, and a conventional optical modulator device often requires attaching several dice on different substrates, where the optical circuits are then fabricated on the different substrates. The conventional optical modulator is unnecessarily large, costly, and limits the performance of the optical circuits. Therefore, it may be desirable to provide a novel optical modulator that is spatially compact for cost efficiency and higher device performance characteristics. Furthermore, it may also be desirable to provide a novel optical modulator that exhibits a low DC bias drift and a high modulation speed. In addition, it may also be desirable to provide a novel method of fabricating the novel optical modulator, which is spatially compact with the low DC bias drift and the high modulation speed.